Google Books Ngram Viewer

Graph these comma-separated phrases:
case-insensitive
between and from the corpus with smoothing of .  
Search in Google Books:

1900 - 1939 1940 - 2001 2002 - 2003 2004 - 2005 2006 - 2008 terrorism English
1900 - 1955 1956 - 2002 2003 - 2004 2005 - 2006 2007 - 2008 terrorist English
1900 - 1934 1935 - 1961 1962 - 1967 1968 - 1999 2000 - 2008 communism English
1900 - 1946 1947 - 1987 1988 - 1993 1994 - 1999 2000 - 2008 communist English

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